In one known type of electronic musical instrument, disclosed in German Patent Specification 29 26 548, a waveform generator, allowing a stored tone to dynamically change over into another stored tone, is described to create the sound in an electronic musical instrument. Further electronic instruments are described in the prior art referred to in German Patent Specification 29 26 548, namely, German "Auslegeschrift" 22 37 594, German "Offenlegungsschrift" 28 30 483, German "Offenlegungsschrift" 28 30 482 and U.S. Pat. No. 3,859,884.
U.S. Pat. No. 4,164,020 describes a programmable sound synthesizer, holding a multiplicity of sound data in a memory. The memory is read through an address generator, whose repeat frequency is controlled by an integrator. The rate of integration is in turn determined by a "tone number." Various sound parameters, such as frequency, waveform, envelope, force of stroke, fading, etc., can be entered. These sound parameters are, however, unchangeable constituents of the stored sound data. Thus the sound data are read cyclically in the numerical sequence of the addresses of the sound data entered. Thus, briefly, only pre-programmed tone sequences can be entered with freely programmable sound characteristics, which, however, can no longer be changed during reproduction; so that, strictly speaking, these are not musical instruments, but, like a gramophone record, only "canned sounds."
The objective of the invention is to improve the aforementioned type of electronic musical instrument so that it is fully and freely programmable, producing any sound, which is also changeable at the time the instrument is played.